// Requirements:
// We are looking for a program that manages “intensity” by segments. Segments are intervals from -infinity to
// infinity, we’d like you to implement functions that updates intensity by an integer amount for a given range.
// All intensity starts with 0. Please implement these three functions:
/**
* This function finds the lower bound of the value k in the array a with n elements
* @param {Array<number>} a - the array of numbers
* @param {number} n - the number of elements in the array
* @param {number} k - the value to find the lower bound of
* @returns {number} - the index of the lower bound of k in the array a
*/
function lowerBound(a, n, k) {
let l = 0,
r = n - 1;
while (l + 1 < r) {
let mid = l + r >> 1;
if (a[mid] <= k) {
l = mid;
} else {
r = mid;
}
}
return l;
}
class IntensitySegments {
/**
* This is the constructor for the IntensitySegments class
* @constructor
* @param {void}
* @return {void}
*/
constructor() {
// first we initialize the map with -Infinity and Infinity set to 0
this.map = new Map();
this.map.set(-Infinity, 0);
this.map.set(Infinity, 0);
this.keys = [-Infinity, Infinity];
}
/**
* This function adds the amount to the intensity of the range from `from` to `to`
* @param {number} from - the start of the range
* @param {number} to - the end of the range (not inclusive)
* @param {number} amount - the amount to add to the intensity
* @return {void}
*/
add(from, to, amount) {
// find lower bound of from and to that is the range that we need to update
let keys = this.keys;
let start = lowerBound(keys, keys.length, from);
let end = lowerBound(keys, keys.length, to);
// update the from
let start_value = this.map.get(keys[start]);
this.map.set(from, start_value + amount);
// update the to
let end_value = this.map.get(keys[end]);
this.map.set(to, end_value);
// update the range between from and to
for (let i = start + 1; i <= end; i++) {
if (keys[i] === from || keys[i] === to) {
continue;
}
let value = this.map.get(keys[i]);
this.map.set(keys[i], value + amount);
}
this.addNewKeys(from, to, start, end);
// merge same values
this.mergeSameValues();
}
/**
* This function sets the intensity of the range from `from` to `to` to the amount
* @param {number} from
* @param {number} to
* @param {number} amount
* @return {void}
*/
set(from, to, amount) {
// same operation as add
let keys = this.keys;
let start = lowerBound(keys, keys.length, from);
let end = lowerBound(keys, keys.length, to);
this.map.set(from, amount);
let end_value = this.map.get(keys[end]);
this.map.set(to, end_value);
for (let i = start + 1; i <= end; i++) {
if (keys[i] === from || keys[i] === to) {
continue;
}
this.map.set(keys[i], amount);
}
this.addNewKeys(from, to, start, end);
// merge same values
this.mergeSameValues();
}
/**
* This function adds new keys to the keys array
* @param {number} from - the from value trying to add
* @param {number} to - the to value trying to add
* @param {number} start - the index of the lower bound of from
* @param {number} end - the index of the lower bound of to
* @return {void}
*/
addNewKeys(from, to, start, end) {
let new_keys = [];
let keys = this.keys;
for (let i = 0; i <= start; i++) {
new_keys.push(keys[i]);
}
if (keys[start] !== from) {
new_keys.push(from);
}
for (let i = start + 1; i <= end; i++) {
new_keys.push(keys[i]);
}
if (keys[end] !== to) {
new_keys.push(to);
}
for (let i = end + 1; i < keys.length; i++) {
new_keys.push(keys[i]);
}
this.keys = new_keys;
}
/**
* This function merges the same values in the map
* @return {void}
*/
mergeSameValues() {
let keys = this.keys;
let new_keys = [];
// console.log('keys', keys);
let prev = keys[0];
new_keys.push(prev);
let prev_value = this.map.get(prev);
for (let i = 1; i < keys.length - 1; i++) {
let key = keys[i];
let value = this.map.get(key);
if (value === prev_value) {
this.map.delete(key);
} else {
new_keys.push(key);
}
prev = key;
prev_value = value;
}
new_keys.push(keys[keys.length - 1]);
this.keys = new_keys;
}
/**
* This function returns the string representation of the segments
* @return {string} - the string representation of the segments
* @override
*/
toString() {
let keys = this.keys;
// console.log('keys', keys);
let result = [];
for (let key of keys) {
if (key === -Infinity || key === Infinity) {
continue;
}
result.push([key, this.map.get(key)]);
}
console.log(JSON.stringify(result));
return JSON.stringify(result);
}
};
// (data stored as an array of start point and value for each segment.)
function test1() {
const segments = new IntensitySegments();
segments.toString(); // Should be "[]"
segments.add(10, 30, 1);
segments.toString(); // Should be: "[[10,1],[30,0]]"
segments.add(20, 40, 1);
segments.toString(); // Should be: "[[10,1],[20,2],[30,1],[40,0]]"
segments.add(10, 40, -2);
segments.toString(); // Should be: "[[10,-1],[20,0],[30,-1],[40,0]]"
}
function test2() {
const segments = new IntensitySegments();
segments.toString(); // Should be "[]"
segments.add(10, 30, 1);
segments.toString(); // Should be "[[10,1],[30,0]]"
segments.add(20, 40, 1);
segments.toString(); // Should be "[[10,1],[20,2],[30,1],[40,0]]"
segments.add(10, 40, -1);
segments.toString(); // Should be "[[20,1],[30,0]]"
segments.add(10, 40, -1);
segments.toString(); // Should be "[[10,-1],[20,0],[30,-1],[40,0]
}
function test3() {
const segments = new IntensitySegments();
segments.toString(); // Should be "[]"
segments.set(10, 30, 1);
segments.toString(); // Should be "[[10,1],[30,0]]"
segments.set(5, 40, 1);
segments.toString(); // Should be "[[5,1],[40,0]]"
segments.add(10, 40, -2);
segments.toString(); // Should be "[[5,1],[10,-1],[40,0]]"
segments.set(-5, 50, 0);
segments.toString(); // Should be "[]"
}
test1();
test2();
test3();
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Javascript(JS) is a object-oriented programming language which adhere to ECMA Script Standards. Javascript is required to design the behaviour of the web pages.
var readline = require('readline');
var rl = readline.createInterface({
input: process.stdin,
output: process.stdout,
terminal: false
});
rl.on('line', function(line){
console.log("Hello, " + line);
});
| Keyword | Description | Scope |
|---|---|---|
| var | Var is used to declare variables(old way of declaring variables) | Function or global scope |
| let | let is also used to declare variables(new way) | Global or block Scope |
| const | const is used to declare const values. Once the value is assigned, it can not be modified | Global or block Scope |
let greetings = `Hello ${name}`
const msg = `
hello
world!
`
An array is a collection of items or values.
let arrayName = [value1, value2,..etc];
// or
let arrayName = new Array("value1","value2",..etc);
let mobiles = ["iPhone", "Samsung", "Pixel"];
// accessing an array
console.log(mobiles[0]);
// changing an array element
mobiles[3] = "Nokia";
Arrow Functions helps developers to write code in concise way, it’s introduced in ES6.
Arrow functions can be written in multiple ways. Below are couple of ways to use arrow function but it can be written in many other ways as well.
() => expression
const numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
const squaresOfEvenNumbers = numbers.filter(ele => ele % 2 == 0)
.map(ele => ele ** 2);
console.log(squaresOfEvenNumbers);
let [firstName, lastName] = ['Foo', 'Bar']
let {firstName, lastName} = {
firstName: 'Foo',
lastName: 'Bar'
}
const {
title,
firstName,
lastName,
...rest
} = record;
//Object spread
const post = {
...options,
type: "new"
}
//array spread
const users = [
...adminUsers,
...normalUsers
]
function greetings({ name = 'Foo' } = {}) { //Defaulting name to Foo
console.log(`Hello ${name}!`);
}
greet() // Hello Foo
greet({ name: 'Bar' }) // Hi Bar
IF is used to execute a block of code based on a condition.
if(condition){
// code
}
Else part is used to execute the block of code when the condition fails.
if(condition){
// code
} else {
// code
}
Switch is used to replace nested If-Else statements.
switch(condition){
case 'value1' :
//code
[break;]
case 'value2' :
//code
[break;]
.......
default :
//code
[break;]
}
For loop is used to iterate a set of statements based on a condition.
for(Initialization; Condition; Increment/decrement){
//code
}
While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.
while (condition) {
// code
}
Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.
do {
// code
} while (condition);
ES6 introduced classes along with OOPS concepts in JS. Class is similar to a function which you can think like kind of template which will get called when ever you initialize class.
class className {
constructor() { ... } //Mandatory Class method
method1() { ... }
method2() { ... }
...
}
class Mobile {
constructor(model) {
this.name = model;
}
}
mbl = new Mobile("iPhone");